The information provided below is not admitted to be prior art to the present invention, but is provided solely to assist the understanding of the reader.
This invention relates to stain resistant polymeric compositions for the treatment of natural and synthetic fibers. Approximately 75% of all carpet currently produced in the United States, and approximately half of all carpet produced in Europe, is prepared from nylon fiber.
Nylon fiber is relatively inexpensive and offers a combination of desirable qualities such as comfort, warmth, and ease of manufacture into a broad range of colors, patterns and textures. However, nylon, as well as other polyamide fibers and fabrics, is easily stained by certain natural and artificial colorants such as those found in coffee, mustard, wine, and soft drinks.
Fluorochemical coatings have been developed that are effective in protecting carpet from substances such as soil. However, they offer little protection from stains resulting from acid dyes that are found in common household materials such as wine, mustard and soft drinks. Acid dyes are chromophores containing sodium salt of sulfonic acid. The sulfonic acid groups bind the protonated amine ends to the polyamide. A wide variety of methods have been developed to make polyamide fibers or other fibers with terminal amino groups more resistant to staining by acid dyes.
Sulfonated hydroxyaromatic formaldehyde condensate coatings have been disclosed to reduce the staining of polyamide fibers by acid dyes. However, such polymers do not impart resistance to staining by turmeric-containing compounds such as mustard, or by hot coffee. Moreover, ultraviolet light and nitrogen dioxide can yellow such polymers over time. The yellowing can be severe enough to prevent the use of such stain-resist compositions on light shaded textile articles.
Stain-resists based on hydrolyzed copolymers derived from maleic anhydride and ethylenically unsaturated compounds are known. Examples include hydrolyzed copolymers of maleic anhydride with α-olefins. Maleic acid/α-olefin copolymers have been disclosed to impart good anti-staining properties to polyamide substrates. In addition, such polymers resist yellowing. Because of the ionic character of hydrolyzed maleic anhydride copolymer stain-resists, polyamide substrates treated with such stain-resist agents tend to be sensitive to high pH values, which is often encountered in commercial carpet shampoos. Consequently, stain resistance can be partially or completely lost following shampooing. Methacrylic acid homopolymers and copolymers, as well as other carboxylated polymers, are also known as stain-resists. They behave similarly towards polyamide substrates as the hydrolyzed maleic anhydride/α-olefin copolymers.
Compositions based on sulfonated phenol-formaldehyde condensates combined with hydrolyzed maleic anhydride/α-olefin copolymers or polymers of methacrylic acid, when applied to polyamide substrates, provide acid stain resistance and overcome the yellowing caused by UV and/or nitrogen oxides. However, the stain resistance does not survive shampooing, especially at high pH.
U.S. Pat. No. 5,356,689 and U.S. Pat. No. 5,358,769 (Pechhold), assigned to the assignee of the present invention, disclose means to render stain-resist agents less soluble by cross-linking the stain-resist agent to the polyamide fibers. Pechhold discloses co-applying the combined stain-resist agents described above with a water-dispersed epoxy resin or by post-treatment of the stain-resist-treated polyamide fiber substrate with a water-dispersed epoxy resin. The Pechhold process prevents excessive dissolution of the stain-resist agents during alkaline shampoo treatment.
Stain-resist performance of conventional compositions is typically tested by determining the amount of stain imparted by solutions of F&C Red Dye 40, or other acid dyes typically present in beverages and foods. U.S. Pat. No. 5,118,551 (Calcaterra) discloses that most stain-resist agents are ineffective against coffee staining. Calcaterra further discloses that a copolymer selected from the group consisting of hydrolyzed aromatic-containing vinyl ether maleic anhydride copolymers, and half esters of aromatic-containing vinyl ether maleic anhydride copolymers, provided polyamide textiles with stain resistance against coffee. However, stain resistance was lost upon detergent washing at high pH.
Conventional stain-resist agents impart to polyamide substrates resistance against staining by either acid dyes or coffee, but the stain resistance cannot be sustained after repeated shampooing. In addition, none of the stain-resist agents can be used for stain resisting to staining of both acid dyes and hot coffee. Therefore, there exists a need to provide maleic acid/α-olefin stain-resist compositions having both superior resistance to staining by acid dyes and/or coffee and superior resistance to high pH detergent washing.
Other objects and advantages will become apparent from the following disclosure.